当前位置： SCI文献检索 > Geobiology期刊下所有文献 > The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils.

The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils.

Abstract：

:The well-known debate on the nature and origin of intracellular inclusions (ICIs) in silicified microfossils from the early Neoproterozoic Bitter Springs Formation has recently been revived by reports of possible fossilized nuclei in phosphatized animal embryo-like fossils from the Ediacaran Doushantuo Formation of South China. The revisitation of this discussion prompted a critical and comprehensive investigation of ICIs in some of the oldest indisputable eukaryote microfossils-the ornamented acritarchs Dictyosphaera delicata and Shuiyousphaeridium macroreticulatum from the Paleoproterozoic Ruyang Group of North China-using a suite of characterization approaches: scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam scanning electron microscopy (FIB-SEM). Although the Ruyang acritarchs must have had nuclei when alive, our data suggest that their ICIs represent neither fossilized nuclei nor taphonomically condensed cytoplasm. We instead propose that these ICIs likely represent biologically contracted and consolidated eukaryotic protoplasts (the combination of the nucleus, surrounding cytoplasm, and plasma membrane). As opposed to degradational contraction of prokaryotic cells within a mucoidal sheath-a model proposed to explain the Bitter Springs ICIs-our model implies that protoplast condensation in the Ruyang acritarchs was an in vivo biologically programmed response to adverse conditions in preparation for encystment. While the discovery of bona fide nuclei in Paleoproterozoic acritarchs would be a substantial landmark in our understanding of eukaryote evolution, the various processes (such as degradational and biological condensation of protoplasts) capable of producing nuclei-mimicking structures require that interpretation of ICIs as fossilized nuclei be based on comprehensive investigations.

journal_name

Geobiology

journal_title

Geobiology

authors

Pang K,Tang Q,Schiffbauer JD,Yao J,Yuan X,Wan B,Chen L,Ou Z,Xiao S

doi

10.1111/gbi.12053

subject

Has Abstract

pub_date

2013-11-01 00:00:00

pages

499-510

issue

eissn

1472-4677

issn

1472-4669

journal_volume

pub_type

杂志文章

在线工具

The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils.